Enhancing resonant features in the aspect dependence of target spectra by reversible imaging filtration techniques.

Abstract

The aspect dependence of the spectral response of simple objects is sometimes examined in scattering research. The use of reversible imaging algorithms for the approximate de‐coupling of the impulse response and associated spectral‐responses of two adjacently located targets with overlapping signals was previously demonstrated [T. M. Marston, P. L. Marston, and K. L. Williams, J. Acoust. Soc. Am. 127, 1749 (2010)]. The current research concerns how resonant features of targets can be enhanced by using related imaging and filtering algorithms. When resonant targets are imaged using synthetic aperture techniques, the resonant portion is often distinct enough from specular or edge‐diffraction portions so that it is possible to design spatial filters that isolate the resonant from the non‐resonant portions of the signal in the image domain. The filtered image is then returned to the original domain, and frequency response is plotted with the non‐resonant portions of the data filtered out. The resulting plots show enhanced resonant features. Demonstrations using line‐scan SAS and circular SAS data will be shown. [Work supported by ONR.]